Algorithmic and sensor-based research on Chinese children's and adolescents' screen use behavior and light environment.

Background: Myopia poses a global health concern and is influenced by both genetic and environmental factors. The incidence of myopia tends to increase during infectious outbreaks, such as the COVID-19 pandemic. This study examined the screen-time behaviors among Chinese children and adolescents and investigated the efficacy of artificial intelligence (AI)-based alerts in modifying screen-time practices. Methods: A cross-sectional analysis was performed using data from 6,716 children and adolescents with AI-enhanced tablets that monitored and recorded their behavior and environmental light during screen time. Results: The median daily screen time of all participants was 58.82 min. Among all age groups, elementary-school students had the longest median daily screen time, which was 87.25 min and exceeded 4 h per week. Children younger than 2 years engaged with tablets for a median of 41.84 min per day. Learning accounted for 54.88% of participants' screen time, and 51.03% (3,390/6,643) of the participants used tablets for 1 h at an average distance <50 cm. The distance and posture alarms were triggered 807,355 and 509,199 times, respectively. In the study, 70.65% of the participants used the tablet under an illuminance of <300 lux during the day and 61.11% under an illuminance of <100 lux at night. The ambient light of 85.19% of the participants exceeded 4,000 K color temperature during night. Most incorrect viewing habits (65.49% in viewing distance; 86.48% in viewing posture) were rectified swiftly following AI notifications (all p < 0.05). Conclusion: Young children are increasingly using digital screens, with school-age children and adolescents showing longer screen time than preschoolers. The study highlighted inadequate lighting conditions during screen use. AI alerts proved effective in prompting users to correct their screen-related behavior promptly.

Characterization the corneal transparency profile in SMILE-treated myopic patients with densitometry: A 7-year cohort study.

PURPOSE: To investigate 7-year changes in corneal densitometry (CD) and its influencing factors following small incision lenticule extraction (SMILE) for moderate to high myopia. METHODS: A total of 32 patients (52 eyes) with a mean spherical equivalent (SE) refraction of -6.30 ± 1.30 D who underwent SMILE were recruited for this prospective study. Pre- and postoperative CD and corneal aberrations were measured by an oculus Pentacam system, and patients were followed up to 7 years. The CD evolution over time and its influencing factors were explored. RESULTS: No complications were observed after SMILE. There was a significant time effect on postoperative CD ( P < 0.05). The CD values at the 0-to-2 and 2-to-6 mm of the anterior layer increased at the first day ( P < 0.05) and declined to baselines at 1 year postoperatively; after that, CD values at any zone and any corneal layer presented a decreasing trend over time (all P < 0.05). Multivariate analysis showed that postoperative CD was positively correlated with age and optical zone (OZ), whereas negatively correlated with SE, corrected distance visual acuity (CDVA), and corneal aberrations (higher-order aberrations, Coma0 and Coma90) (all P < 0.05). Generalized estimating equation revealed that age, SE, CDVA, OZ, and Coma0 were the main factors influencing postoperative CD values (all P < 0.05). CONCLUSION: CD manifested a long-term decreasing trend in moderate to high myopia treated with SMILE. Its main influencing factors are age, SE, CDVA, OZ, and Coma0.

Characteristics of disk halo size and its correlation with lenticule quality in small incision lenticule extraction for moderate to high myopia.

PURPOSE: To investigate changes in disk halo size after small incision lenticule extraction (SMILE) and the correlation between halo size and lenticule quality in moderate to high myopia. METHODS: Thirty eyes of 30 consecutive patients (mean age, 24.9 ± 4.5 years; mean spherical equivalent, -6.85 ± 1.18 D) undergoing SMILE were included in this prospective study. Lenticule surface quality was accessed with a scanning electron microscopy by a scoring system. Halo size was measured preoperatively and at 1, 3, and 6 months postoperatively. Multiple linear regression analysis was performed to explore associations between halo size and a range of factors, including lenticule quality. RESULTS: Disk halo size increased slightly at 1 month and then recovered continually from 3 to 6 months postoperatively, with no difference between halo size during the preoperative period and at 6 months postoperatively (P > 0.05). One month after SMILE, halo size (1 cd/m2, 5 cd/m2) was associated only with uncorrected distance visual acuity (P ≤ 0.004). A halo size of 5 cd/m2 at 3 months postoperatively correlated with the anterior surface quality of the lenticule (P = 0.046). At 6 months postoperatively, a halo size of 1 cd/m2 was associated only with the baseline, accounting for 11.9% of the variability (P = 0.041); no correlations were found for the halo size of 5 cd/m2. CONCLUSIONS: Disk halo size after SMILE was enlarged at an early stage postoperatively and subsequently declined to the baseline level during a 6-month follow-up. The quality of the lenticule surface influenced halo size changes in the early phase.

Evaluation of visual plasticity in patients with refractive amblyopia treated using a visual perceptual learning system.

BACKGROUND: Amblyopia is a neurological deficit in binocular vision that affects 3% of the population and is the result of disruptions in early visual development. OBJECTIVE: In this study, we used a visual perceptual learning system for the short-term treatment of children with ametropic amblyopia and evaluated the clinical efficacy of this system in terms of visual plasticity. METHODS: We conducted a retrospective analysis of the clinical data of 114 children (228 eyes) with refractive amblyopia, who were aged 6.51 ± 1.51 years. Prior to the treatment, we evaluated all children with amblyopia using the visual information processing test. We determined the type of amblyopic defect according to the type of amblyopia, corrected visual acuity, and advanced visual function test results. Based on the type of defect, each child with amblyopia was given short-term visual perception training for 10 days. Finally, we compared the results of visual acuity and visual information processing tests before and after the treatment. RESULTS: The best-corrected visual acuity of patients was better after 10 days of visual training than that before training (P< 0.05). The perceptual eye position after training improved with statistically significant differences in horizontal and vertical perceptual eye position (both P< 0.05) compared to that before training. The number of amblyopic children without suppression in both eyes was 81 cases (71.1%) after training which was higher than that (65 cases, or 57.0%) before training, with a statistically significant difference (P< 0.05). Binocular fine stereopsis and dynamic stereopsis improved after training with a statistically significant difference (both P< 0.05). CONCLUSION: In this study, it was found that patients with amblyopia showed visual plasticity. Moreover, continuous visual perceptual learning improved the best-corrected visual acuity and recovered stereopsis in children with refractive amblyopia.

Influencing Factors of Glare in Patients With Myopia After Small Incision Lenticule Extraction.

PURPOSE: To investigate influencing factors of glare in patients with myopia after small incision lenticule extraction (SMILE). METHODS: Thirty patients (60 eyes) aged 24.9 ± 4.5 years with spherical equivalent of -6.69 ± 1.10 diopters (D) and astigmatism of -1.25 ± 0.76 D who underwent SMILE were consecutively recruited in this prospective study. Visual acuity, subjective refraction, Pentacam corneal topography (Oculus Optikgeräte GmbH), pupillometry, and glare test (Monpack One; Metrovision) were measured preoperatively and postoperatively. All patients were followed up for 6 months. The generalized estimation equation was used to judge the determinants of glare after SMILE, and a P value less than .05 was statistically significant. RESULTS: Under mesopic conditions, the halo radii preoperatively and at 1, 3, and 6 months after SMILE were 207.72 ± 46.67, 216.17 ± 40.63, 200.67 ± 34.68, and 193.50 ± 40.75 minutes of arc (arcmin), respectively. Under photopic conditions, the glare radii were 79.10 ± 17.78, 87.00 ± 20.44, 78.00 ± 14.59, and 72.00 ± 15.27 arcmin, respectively. Compared with preoperative glare, no significant changes were detected in postoperative glare. However, glare at 6 months was statistically significantly improved compared to the values at 1 month (both P < .05). Under mesopic conditions, the main influencing factors of glare were sphere (P = .007), astigmatism (P = .032), uncorrected distance visual acuity (UDVA) (P < .001), and postoperative time (all P < .05). Under photopic conditions, the main influencing factors of glare were astigmatism, UDVA, and postoperative time (all P < .05). CONCLUSIONS: Glare improved with time during the early stages after SMILE for myopia. Less glare was found to be associated with better UDVA, and greater residual astigmatism and sphere translated to more obvious glare. [J Refract Surg. 2023;39(6):398-404.].

A novel quick contrast sensitivity function test in Chinese adults with myopia and its related parameters.

PURPOSE: This study is to investigate the contrast sensitivity function (CSF) using the quick CSF (qCSF) test in Chinese adults with myopia. METHODS: This case series study included 320 myopic eyes of 160 patients (mean age 27.75 ± 5.99 years) who underwent a qCSF test for acuity, area under log CSF (AULCSF), and mean contrast sensitivity (CS) at 1.0, 1.5, 3.0, 6.0, 12.0, and 18.0 cycle per degree (cpd). Spherical equivalent, corrected-distant visual acuity (CDVA), and pupil size were recorded. RESULTS: The spherical equivalent, CDVA (LogMAR), spherical refraction, cylindrical refraction, and the scotopic pupil size of the included eyes were - 6.30 ± 2.27 D (- 14.25 to - 0.88 D), 0 ± 0.02, - 5.74 ± 2.18 D, - 1.11 ± 0.86 D, and 6.77 ± 0.73 mm, respectively. The AULCSF and CSF acuity were 1.01 ± 0.21 and 18.45 ± 5.39 cpd, respectively. The mean CS (log units) at six different spatial frequencies were 1.25 ± 0.14, 1.29 ± 0.14, 1.25 ± 0.14, 0.98 ± 0.26, 0.45 ± 0.28, and 0.13 ± 0.17, respectively. A mixed effect model showed significant correlations between age and acuity, AULCSF, and CSF at 1.0, 12.0, and 18.0 cpd. Interocular CSF differences were correlated with the interocular difference of spherical equivalent, spherical refraction (at 1.0 cpd, 1.5 cpd), and cylindrical refraction (at 12.0 cpd, 18.0 cpd). The lower cylindrical refraction eye had higher CSF compared with the higher cylindrical refraction eye (0.48 ± 0.29 vs. 0.42 ± 0.27 at 12.0 cpd and 0.15 ± 0.19 vs. 0.12 ± 0.15 at 18.0 cpd). CONCLUSIONS: The age-related decrease in contrast sensitivity is at low and high spatial frequencies. Higher-degree myopia may show a decrease in CSF acuity. Low astigmatism was noted to affect the contrast sensitivity significantly.

The Characteristics of Quick Contrast Sensitivity Function in Keratoconus and Its Correlation with Corneal Topography.

INTRODUCTION: To characterize quick contrast sensitivity function (qCSF) in keratoconus and its correlation with corneal topographic parameters. METHODS: Patients with keratoconus (n = 120) who visited the Fudan Eye and ENT Hospital between April and June 2021 were enrolled in our study. A total of 215 eyes were subdivided into three groups according to maximum keratometry (Kmax): Group 1 (Kmax ≤ 48 D, 74 eyes), Group 2 (48 D < Kmax ≤ 55 D, 64 eyes), and Group 3 (Kmax > 55 D, 77 eyes). Manifest refraction, best corrected distance visual acuity (BCVA), corneal topography, and the qCSF test were examined. Intergroup comparisons and correlations among various corneal topographic parameters and qCSF were analyzed. RESULTS: Significant differences in the area under the log CSF (AULCSF) and CSF Acuity among the three groups were found, which decreased with an increase in Kmax. Contrast sensitivity (CS) between spatial frequencies of 3.0 to 18.0 cpd was significantly different (all P < 0.05) between Groups 1 and 2. The CS at all spatial frequencies was significantly different (all P < 0.05) between Group 3 and other two groups. At 3.0-18.0 cpd, CS decreased significantly (all P < 0.05) in Groups 1-3. Manifest refraction and topographic indices correlated significantly with qCSF parameters (all P < 0.05). Multivariable linear regression analysis showed that cylindrical refraction, logMAR BCVA, and index of surface variance had good predictive values for AULCSF and CSF Acuity. CONCLUSIONS: The use of qCSF test can serve as a feasible tool to evaluate visual quality and severity of keratoconus, since changes in CS significantly correlated with keratoconus severity.

Evaluating early-stage disk halo changes after small incision lenticule extraction.

PURPOSE: To investigate early changes in the disk halo under different light conditions after myopic small incision lenticule extraction (SMILE). METHODS: This prospective study included 70 eyes of 70 myopic patients aged 18-33 years, with a spherical equivalent (SE) of -5.87 ± 1.86 D, who underwent SMILE. The subjective refraction, higher-order aberrations (HOAs), pupillometry, and halo were measured preoperatively and postoperatively to analyse disk halo variations and correlated factors. RESULTS: At 5 cd/m2 and 1 cd/m2 luminance, the halo radius in the high myopia (HM) group reached a postoperative peak after 1 week (p = 0.000 and 0.019, respectively), and recovered to baseline after 3 months. In the low-to-moderate (LM) myopia group, the halo radius did not differ 1 week postoperatively compared to the preoperative level (p = 0.015), but significantly improved after 3 months (p = 0.000). The halo radius correlated with SE, uncorrected distance visual acuity (UDVA), ocular HOAs, coma, and the pupillary light reflex in the LM group at all time points, but there were no correlations in the HM group. CONCLUSIONS: Halo symptoms occurred early after SMILE, but recovered within 3 months. The recovery process was slower in the HM group than in the LM group, and the halo radius correlated with SE, UDVA, ocular HOAs, coma, and the pupillary light reflex.

Long-term changes in corneal densitometry and associated factors following small incision lenticule extraction for moderate and high myopia.

Purpose: To investigate long-term trends in corneal densitometry and associated influencing factors following small incision lenticule extraction (SMILE). Methods: A comparative study was performed among 72 eyes of 38 patients undergoing SMILE. Eyes were divided into moderate myopia [mean spherical equivalent (SE),-4.22 ± 0.68D] and high myopia (mean SE,-7.63 ± 1.09 D) groups. Visual acuity, manifest refraction, corneal topography and corneal densitometry (CD) were evaluated preoperatively and 3 years postoperatively. Results: The efficacy indices at last postoperative follow-up (42.47 ± 0.51 months) were 0.92 ± 0.21 and 0.97 ± 0.22, the safety indices were 1.12 ± 0.17 and 1.14 ± 0.21 for high and moderate myopia, respectively (all P > 0.05). CD values in the 0-6 mm zone of the posterior corneal layer was statistically significantly lower than the preoperative values in both groups. Postoperative CD values (0-2 mm zone) in the posterior layer of the high myopia group were statistically significantly lower than in the moderate myopia group (P = 0.025); CD values (2-6 mm zone) in the anterior layer were higher in the high myopia group (P = 0.026). Correlation analyses showed that CD values in the 0-2 mm middle layer were negatively correlated with lenticule thickness in high myopia (r = -0.411, P = 0.016); there was a negative correlation between the CD values (0-6 mm) and corneal oblique trefoil in this group (P < 0.05). Conclusion: Corneal transparency in the 0-6 mm zone of the posterior cornea increased following SMILE in moderate and high myopia. Long-term CD values in high myopia may be correlated with oblique trefoil and lenticule thickness.

A Comprehensive Investigation of Contrast Sensitivity and Disk Halo in High Myopia Treated With SMILE and EVO Implantable Collamer Lens Implantation.

Purpose: To investigate the clinical outcomes in small incision lenticule extraction (SMILE) and EVO implantable Collamer lens (ICL)-treated high myopia. Methods: Thirty-three SMILE-treated and 32 EVO ICL-treated patients were included and followed up for 6 months. Subjective refraction, contrast sensitivity, and disk halo size were measured preoperatively and postoperatively. Patient-reported outcomes (PROs) were obtained at the final visit. Results: Significant differences in efficacy and safety indices were observed between the SMILE and EVO ICL groups at 6 months postoperatively (P < 0.05). In the SMILE group, the mesopic contrast sensitivity at 2.2 cycles per degree (cpd) and photopic contrast sensitivity at 0.5, 3.4, and 7.1 cpd were significantly improved. In the EVO ICL group, the mesopic contrast sensitivity at 7.1 cpd and photopic contrast sensitivity at 0.5, 7.1, and 14.6 cpd were significantly improved. The halo radii after SMILE were significantly increased at 1 week, showed a decreasing trend at 1 month, returned to baseline at 3 months, and progressed stably at 6 months. However, it was unchanged in the EVO ICL group. Regarding subjective experience, haloes were the most common disturbance with mild and little bothersomeness after EVO ICL in contrast to starbursts after SMILE. Conclusions: EVO ICL implantation yielded better visual outcomes, improved contrast sensitivity particularly at high spatial frequencies, had a stabler disk halo size, and increased incidence of haloes, with less influence than that of SMILE. Translational Relevance: The disk halo and PRO findings will be of benefit for consultations and evaluations in visual performance and disturbances.

Evaluation of Disk Halo Size and Identification of Correlated Factors in Myopic Adults.

This study aimed to evaluate glare source-induced disk halo size and assess its correlation with higher-order aberrations (HOAs), pupillometry findings, and contrast sensitivity in myopic adults (aged 23.8 ± 4.4 years). In this cross-sectional study, 150 eyes of 150 patients were assessed. All patients underwent routine ophthalmic examinations, wavefront aberrometry, halo size measurement, dynamic pupillometry, and contrast sensitivity tests. Spearman's correlation analysis and independent sample t-tests were performed for data analysis. The mean halo radius was 82.5 ± 21.8 and 236.7 ± 52.2 arc min at 5 and 1 cd/m2 luminance levels, respectively. The values were inversely correlated with internal spherical aberration (SA) (r = -0.175, p = 0.032 and r = -0.241, p = 0.003, respectively), but not correlated with spherical equivalent (SE, both p > 0.05). Positive correlations were observed between halo radius and pupil size, contraction amplitude, and dilation speed during pupillary light reflex. Halo radii at 5 and 1 cd/m2 luminance levels were not significantly correlated with the area under the log contrast sensitivity function (r = -0.093, p = 0.258 and r = -0.149, p = 0.069, respectively). The mean halo radius was not clinically different between myopic and healthy eyes at 5 cd/m2 luminance level and did not differ significantly between the high and low-to-moderate myopia at 5 and 1 cd/m2 luminance levels (all p > 0.05). According to a stepwise linear regression model, the internal SA had a negative effect on the halo radius under low photpic condition; the average pupil diameter, internal SA and corneal HOAs played a large role in determining the halo radius under mesopic condition.

Nighttime Symptoms After Monocular SMILE: A Contralateral Eye Study.

INTRODUCTION: To investigate nighttime symptoms in patients with myopic anisometropia after monocular small incision lenticule extraction (SMILE) surgery. METHODS: Thirty-six patients who had undergone monocular SMILE more than 6 months previously were recruited at the Eye & ENT Hospital of Fudan University. The average age at surgery was 25.4 ± 6.1 years. Preoperative spherical equivalent (SE) was -3.77 ± 1.56 D in SMILE-treated eyes and -0.08 ± 0.66 D in unoperated eyes. Main measurements included uncorrected and corrected distance visual acuity, manifest refraction, halo radius, contrast sensitivity, nighttime symptoms, and patient satisfaction. RESULTS: The mean follow-up time was 13.9 ± 3.4 months. The efficacy and safety indexes were 1.18 and 1.28, respectively. The halo radius was not significantly different between SMILE-treated and unoperated eyes under luminance conditions of 1, 5, and 100 cd/m2 (P = 0.055). No significant differences were observed in contrast sensitivity at all spatial frequencies between eyes under both uncorrected and corrected conditions (all P > 0.05). None of the patients reported moderate or severe symptoms at night. Mild symptoms (glare, halo, starburst) were reported and binocularly equal in 13 patients, whereas four patients reported better night vision in SMILE-treated eyes than unoperated eyes, and one of them experienced mild night vision disturbance. The overall satisfaction score was 9.39 ± 0.80. CONCLUSIONS: The disk halo size and contrast sensitivity in SMILE-treated eyes were similar to those in unoperated eyes, and nighttime symptoms almost completely resolved after SMILE.

Effect of the Difference Between the White-to-White and Sulcus-to-Sulcus on Vault and the Related Factors After ICL Implantation.

INTRODUCTION: To assess the differences between the horizontal white-to-white (WTW) and horizontal sulcus-to-sulcus (STS) diameter measurements, their related factors, and their effects on vault after implantable Collamer lens (ICL) implantation. METHODS: This retrospective study included 429 eyes of 429 patients (145 men and 284 women with a mean age of 29.22 ± 8.06 years) who underwent ICL implantation. The choice of the ICL size depended on the WTW diameter and anterior chamber depth (ACD). The information of WTW diameter, STS diameters, ACD, and their relationships on vault were analyzed. RESULTS: Horizontal STS and WTW diameters were correlated (r = 0.71, P < 0.001). The mean difference between the STS and WTW diameters was -0.02 ± 0.33 (-1.36 to 1.11) mm. The average vaults of the △STS-WTW < -0.1 group, - 0.1 ≤ △STS-WTW ≤ 0.1 group, and △STS-WTW > 0.1 group were 558.36 ± 163.58 (250-1100) µm, 513.10 ± 121.42 (190-850) µm, and 469.01 ± 133.23 (120-750) µm, respectively. There were significant differences between these groups (P < 0.05). △STS-WTW was correlated with the horizontal STS diameter (r = 0.30, P < 0.001), the WTW diameter (r = -0.17, P = 0.001), and the ACD (r = 0.17, P < 0.001). When the WTW diameter was further away from 11.08 to 12.51 mm or the ACD was further away from 2.81 to 3.74 mm, the difference between the STS and WTW diameters was larger and the correlation between the STS and WTW diameters was weaker. CONCLUSIONS: The difference between the WTW and STS diameters was larger for cases with a WTW diameter or anterior chamber depth outside a certain range; this may be associated with an undesirable vault after ICL implantation. Special attention should be paid to these patients.

Comparison of Corneal Biomechanical Properties between Post-LASIK Ectasia and Primary Keratoconus.

PURPOSE: To compare the corneal biomechanical properties between post-LASIK ectasia and primary keratoconus. METHODS: A total of 42 eyes of 42 patients with matching age and central corneal thickness (CCT) were divided into two groups according to diagnosis of post-LASIK ectasia (PLE group; n = 21; age range: 22-47 years) and primary keratoconus (KC group; n = 21; age range: 21-47 years). The corneal biomechanical properties were assessed using Scheimpflug-based technology (Corvis ST; Oculus Optikgeräte, Wetzlar, Germany). The paired t-test and linear regression analysis were performed. RESULTS: The PLE group had significantly higher mean stiffness parameter at the first applanation (SP-A1; 76.65 ± 21.66 vs 52.72 ± 13.65, p ≤ 0.001) and mean stress-strain index (SSI) (SSI: 0.78 ± 0.16 versus 0.64 ± 0.12, p=0.001) than the KC group. SP-A1 was positively correlated with CCT in the PLE group (Pearson's r = 0.816, p ≤ 0.001), but not in the KC group (Pearson's r = -0.014, p=0.952). No statistical correlation was observed between SSI and CCT in either group (Pearson's r = 0.292, p=0.199, and Pearson's r = 0.004, p=0.985, respectively). CONCLUSIONS: In our case series, KC manifested more severe than PLE in biomechanical properties. Since SSI measurements were independent of corneal thickness, it can be used for corneal biomechanical assessment.

The effects of monocular training on binocular functions in anisometropic amblyopia.

Intensive monocular perceptual learning can improve visual acuity, contrast sensitivity, and vernier acuity in the amblyopic eye in adults with amblyopia. It is however not clear how much monocular training can enhance binocular visual functions. In the current study, we aimed to evaluate effects of monocular training on a variety of binocular functions. Nineteen anisometropic amblyopes (18.5±1.26yrs, mean±s.e.) were trained in a grating contrast detection task near each individual's cutoff spatial frequency for 6-10days (630 trials/day). Visual acuity, stereoacuity, monocular and binocular contrast sensitivity functions (CSF), binocular phase combination and binocular rivalry were tested before and after training. Although monocular training can improve visual acuity and contrast sensitivity and eye dominance of the amblyopic eye, the magnitudes of improvements did not correlate with each other; the impact of monocular training on binocular phase combination was not significant. The results strongly suggest that structured monocular and binocular training is needed to fully recover deficient visual functions in anisometropic amblyopia.

A complete investigation of monocular and binocular functions in clinically treated amblyopia.

The gold standard of a successful amblyopia treatment is full recovery of visual acuity (VA) in the amblyopic eye, but there has been no systematic study on both monocular and binocular visual functions. In this research, we aimed to quantify visual qualities with a variety of perceptual tasks in subjects with treated amblyopia. We found near stereoacuity and pAE dominance in binocular rivalry in "treated" amblyopia were largely comparable to those of normal subjects. CSF of the pAE remained deficient in high spatial frequencies. The binocular contrast summation ratio is significantly lower than normal standard. The interocular balance point is 34%, indicating that contrast in pAE is much less effective as the same contrast in pFE in binocular phase combination. Although VA, stereoacuity and binocular rivalry at low spatial frequency in treated amblyopes were normal or nearly normal, the pAE remained "lazy" in high frequency domain, binocular contrast summation, and interocular phase combination. Our results suggest that structured monocular and binocular training are necessary to fully recover deficient functions in amblyopia.

Perceptual learning improves neural processing in myopic vision.

Visual performance is jointly determined by the quality of optical transmission of the eye and neural processing in the visual system. An open question is: Can effects of optical defects be compensated by perceptual learning in neural processing? To address this question, we conducted a perceptual learning study on 23 observers with myopic vision, targeting high frequency deficits by training them in a monocular grating detection task in the non-dominant eye near their individual cutoff spatial frequencies. The contrast sensitivity function and visual acuity in both eyes (without optical correction) were assessed for all the observers in the training group before and after training, and for all the observers in the control group twice with a 10-day interval between the tests. In addition, the threshold versus external noise contrast function was measured for five observers in the training group before and after training. We found that (a) training significantly improved contrast sensitivity at the trained spatial frequency, visual acuity, and contrast sensitivity over a wide range of spatial frequencies in both eyes; (b) training did not lead to any significant refractive changes; (c) the mechanism of improvements was a combination of internal additive noise reduction and external noise exclusion; and (d) the improvements in visual acuity and contrast sensitivity were almost fully retained for at least four months in the three observers tested. These results suggest that perceptual learning may provide a potential noninvasive procedure to compensate for optical defects in mild to modest myopia.

Prevalence of high astigmatism in children aged 3 to 6 years in Guangxi, China.

PURPOSE: To investigate the prevalence and type of high astigmatism among children aged 3 to 6 years in Guangxi, a relatively undeveloped province in western China, and to examine the correlation between astigmatism and visual acuity. METHODS: Children aged 3 to 6 years in Nanning, the capital of Guangxi Province, participated in a population-based survey using a cluster random sampling technique. Eye examinations included autorefraction, visual acuity measurements, and assessments of the external eye, anterior segment, media, and fundus. Data for the right eyes were analyzed. RESULTS: Among the 2304 children examined, the overall prevalence of high astigmatism (≥1.25 diopters by noncycloplegic SureSight autorefraction) was 12.7% (95% confidence interval, 11.3 to 14.0%). The age-specific prevalences of high astigmatism in 3-, 4-, 5-, and 6-year-old children were 13.8, 13.2, 12.9, and 8.1%, respectively. The prevalence of high astigmatism did not vary with age or gender (p > 0.05). The majority of cases of high astigmatism were with-the-rule astigmatism (82.9%), followed by against-the-rule (12.6%) and oblique (4.5%) astigmatism. A linear correlation was found between astigmatism magnitude and visual acuity (logMAR acuity = 0.068 + 0.055 × astigmatism) in all participants. Multiple linear regression analysis further showed that the correlation of astigmatism with visual acuity was magnitude dependent (ß = 0.240). When with-the-rule astigmatism was used as a reference group, against-the-rule astigmatism (ß = 0.137) and oblique astigmatism (ß = 0.154) were closely correlated with visual acuity. CONCLUSIONS: High astigmatism was moderately prevalent among children aged 3 to 6 years in Guangxi Province. With-the-rule astigmatism was the dominant form of astigmatism. Magnitude- and orientation-dependent correlations of astigmatism with visual acuity were confirmed.

[Prevalence of astigmatism in 2023 children with amblyopia].

OBJECTIVE: To investigate the prevalence, type and distribution of astigmatism in children with amblyopia. METHODS: A total of 2023 children with amblyopia (aged 4-11 years, 3657 eyes) were recruited. The prevalence of astigmatism was investigated. RESULTS: Of the 3657 amblyopic eyes, 91.9% presented astigmatism (≥0.5 D). The proportion of eyes with astigmatism decreased with the increasing age. Compound hyperopic astigmatism was the most common type of astigmatism (38.8%) and its prevalence increased with the increasing age in children with amblyopia. Astigmatism with the rule was the most common (90.1%) in the axial distribution test. There were statistical significances in the axial distribution of astigmatism in different age groups. Statistical significances were also found in the degree, type and axis of astigmatism among the children with mild, moderate and severe amblyopia (P<0.05). CONCLUSIONS: The prevalence of astigmatism in children with amblyopia is high but is reduced with age. The age and the degree of amblyopia might be influential factors in the distribution of astigmatism.

Inhibition effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits.

PURPOSE: To observe the inhibitory effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits. MATERIALS AND METHODS: Twenty-seven healthy New Zealand rabbits were selected and underwent Epi-LASIK surgery. According to a self comparison principle, these rabbits were randomly divided into three groups. The first group was treated with tetrandrine eye drops (Tet), the second (negative control, NC) group was treated with pure solvent, and the third group was treated with fluorometholone (FML) solvent. Haze grades of each group were respectively observed by slit lamp exam at half-month, one month, and two months after surgery. After corneal tissues were extracted, optical microscopy, Sirius Red staining, immunohistochemistry, and semi-quantitative RT-PCR tests were conducted, in order to test collagen formation of operated eyes after surgery and expression of transformation growth factor beta 2 (TGF-ß(2)) in corneal stroma. RESULTS: At a half month and one month after surgery, haze grades and type III collagen expression in Tet and FML groups were significantly lower than that in NC groups (P < 0.01). No statistical difference was observed between Tet and FML groups. Immunohistochemistry showed that, at each time point after surgery, expressions of TGF-ß(2) protein in Tet and FML groups were significantly lower than that in the NC group (P < 0.01), whereas there was no statistical difference between Tet and FML groups. The expression level of TGF-ß(2) protein increased, reaching its peak one month after surgery. RT-PCR also showed that, at each point after surgery, the TGF-ß(2) mRNA expression in Tet and FML groups was lower than that in the NC group (P < 0.01), nevertheless no statistical difference was observed between Tet and FML groups. CONCLUSIONS: Like FML, Tet could inhibit haze formation in rabbits after Epi-LASIK surgery, possible through TGF-ß(2)-collagen-III pathway.